面向“货到人”拣选系统的一种随机调度策略

通过“货到人”拣选系统作业流程分析,提出了在分批下发订单任务的情况下的一种随机调度策略。以AGV (automated guided vehicle)完成所有任务的总时间最短为目标函数,以任务分配为决策变量,考虑进行调度时AGV所处的状态以及在完成任务过程中AGV在拣选台的排队等待时间,建立随机调度策略的数学规划模型。利用遗传算法进行求解,通过实例仿真,验证了随机调度策略较调度空闲AGV策略具有更高的拣选效率,同时解决了AGV调度与拣选序列问题,对AGV数量配置具有指导作用。     

差动步行车

本文提出了一种与传统设计不同的、非关节结构步行车设计。该车在结构可靠性,操纵方便性,承载能力,运动特性及造价等方面都占有明显的优势。文中提出了该车的设计原理并讨论了具体的实施方案。     

Weak Password Security: An Empirical Study

ABSTRACT

Portable Document Format (PDF) is a file format developed by Adobe Systems for representing documents in a manner that is independent of the original application software, hardware, and operating system. A PDF file can describe documents containing any combination of text, graphics, and images in a device independent and/or resolution independent format. It is now used everywhere across academic, technical, and governmental institutions. For secure communication, this platform and hardware independent file can be used as a secure cover media for voluminous data concealing. The methods develop so far for data hiding in PDF files satisfy low-embedding characteristics. In this work, we have developed two techniques. The first searches trash spaces in the PDF file and replaces them with the encrypted secret data. The second technique is useful for storing voluminous encrypted secret data without disturbing any format, features, or characteristics of the file. The practical implementation of this has been done on Microsoft platform. Experimental results show the feasibility of the proposed techniques.     

浅谈空间钢结构的发展和展望

概述当前空间钢结构的现状以及空间钢结构的应用范围，为今后的设计提供一点思路。     

江西廖坊水利枢纽拦污浮排设计

为避免水体中的漂浮物堵塞水电站进水口而影响电站的正常运行,一般要在电站进水口前设置拦漂清污装置。但多数电站拦污装置的运行效果不甚理想,而江西廖坊水电站拦污浮排装置的运行效果颇佳,具体设计为：采用浮排、锚头及垂直升降的卷扬机组成浮排装置,浮排由36节双浮筒和挂栅构成,每节长度7.6 m,节间十字铰接可双向转动,浮筒直径0.7 m,挂栅高0.9 m,栅条间距0.2 m,双浮筒下面的栏栅伸入水下1.37 m。重点介绍了该装置的设计特点和设计体会。可为同类工程设计参考。     

小关子水电站机组技术供水系统滤水器易堵塞问题的解决

小关子水电站机组技术供水方式为蜗壳取水的自流减压供水。由于发电用水中含有较多的垃圾物,电站存在技术供水系统滤水器易堵塞的问题。在2009年3月至2010年3月期间,先后对电站全部4台机组实施了解决滤水器易堵塞问题的技术改造。改造后,滤水器没有发生过堵塞情况,改造取得了令人满意的效果,彻底解决了长时间困扰电站的滤水器易堵塞问题。改造方案为,在机组技术供水系统的蜗壳取水口处安装专门设计的取水口拦污罩取代原有的网状拦污栅。该改造方案具有改造费用低、易于实施、改造效果好的特点,可以推广应用于类似水电站,有较高的实用价值。     

白山抽水蓄能电站拦污栅条振动研究

本文介绍了白山抽水蓄能电站进出水口拦污栅条振动的研究方法和成果，通过测量栅条的激振力频率和结构自振频率，判断栅条发生共振的可能性，对栅条疲劳进行了计算，并对栅条寿命作出了估算。     

Conditions in banana ripening using the rack and pit traditional methods and their effect on juice extraction

Traditional banana ripening processes for juice extraction, using the rack and pit methods, were carried out on farm to assess and compare the conditions in the respective ripening chambers and the suitability of the resulting ripe bananas for juice extraction. During ripening, high temperatures (23‐32°C) were attained and ethylene was produced. Ethylene reached peak concentrations of 250 and 500 mg kg⁻¹ for the rack and the pit methods respectively. Owing to the continued respiration of the bananas, the oxygen concentration fell and carbon dioxide accumulated, however the bananas attained a bright yellow colour on ripening. There was a significant difference in environmental conditions between the rack and pit ripening chambers. This did not affect ripening and it was possible to extract juice from bananas ripened by either method. However, some juice extraction failures were encountered. These preliminary studies suggest that the success or failure of banana juice extraction depends partly on conditions of ripening, in particular temperature. © 1999 Society of Chemical Industry     

圆柱齿轮变向机构

在某些机床中,往复运动基本上是用曲柄摇杆机构或曲柄导杆来实现的。由于这两种机构产生的往复运动的速度是变化的,影响了机床的加工质量。提出了一种产生匀速往复运动的方法,产生匀速往复运动是基于齿轮传动具有恒定传动比的特性,齿轮机构由一个主动齿轮和两个从动齿轮组成。主动齿轮被设计成三层,第一层和第三层的齿数是根据往复运动的要求计算确定的,中间层是环形沟槽。提出的这类齿轮机构经过对试制样机的检测,其功能可靠并且有效。     

新能源汽车电池架空心铝型材挤压模设计

针对新能源汽车电池架空心铝型材,设计分流挤压模,结合有限元模拟技术获得铝型材挤压过程中铝合金的流动速度分布情况。分析模拟得到的数据,针对铝合金挤出速度的不均匀性,对模具的芯模结构提出改进方案,改进后的模拟结果显示型材出口处金属流速均匀,试模试验与有限元模拟结果相符,为相关型材的模具结构设计和改进提供了指导。